For objects having a diffuse surface with lambertian reflection characteristics, there has been considerable attention given to 3D shape reconstruction using structured light. As one example, a survey of various techniques is described by Geng, “Structured-light 3D surface imaging: a tutorial,” Advances in Optics and Photonics, vol. 3, pages 128-160 (2011). As used herein, “shape reconstruction” is sometimes referred to also as “depth estimation”.